I've been trying to setup a Webmachine app on Heroku, using the buildpack recommended. My Procfile is
# Procfile
web: sh ./rel/app_name/bin/app_name console
Unfortunately this doesn't start the dyno correctly, it fails with
2015-12-08T16:34:55.349362+00:00 heroku[web.1]: Starting process with command `sh ./rel/app_name/bin/app_name console`
2015-12-08T16:34:57.387620+00:00 app[web.1]: Exec: /app/rel/app_name/erts-7.0/bin/erlexec -boot /app/rel/app_name/releases/1/app_name -mode embedded -config /app/rel/app_name/releases/1/sys.config -args_file /app/rel/app_name/releases/1/vm.args -- console
2015-12-08T16:34:57.387630+00:00 app[web.1]: Root: /app/rel/app_name
2015-12-08T16:35:05.396922+00:00 app[web.1]: 16:35:05.396 [info] Application app_name started on node 'app_name@127.0.0.1'
2015-12-08T16:35:05.388846+00:00 app[web.1]: 16:35:05.387 [info] Application lager started on node 'app_name@127.0.0.1'
2015-12-08T16:35:05.399281+00:00 app[web.1]: Eshell V7.0 (abort with ^G)
2015-12-08T16:35:05.399283+00:00 app[web.1]: (app_name@127.0.0.1)1> *** Terminating erlang ('app_name@127.0.0.1')
2015-12-08T16:35:06.448742+00:00 heroku[web.1]: Process exited with status 0
2015-12-08T16:35:06.441993+00:00 heroku[web.1]: State changed from starting to crashed
But when I run the same command via heroku toolbelt, it starts up with the console.
$ heroku run "./rel/app_name/bin/app_name console"
Running ./rel/app_name/bin/app_name console on tp-api... up, run.4201
Exec: /app/rel/app_name/erts-7.0/bin/erlexec -boot /app/rel/app_name/releases/1/app_name -mode embedded -config /app/rel/app_name/releases/1/sys.config -args_file /app/rel/app_name/releases/1/vm.args -- console
Root: /app/rel/app_name
Erlang/OTP 18 [erts-7.0] [source] [64-bit] [smp:8:8] [async-threads:10] [hipe] [kernel-poll:false]
16:38:43.194 [info] Application lager started on node 'app_name@127.0.0.1'
16:38:43.196 [info] Application app_name started on node 'app_name@127.0.0.1'
Eshell V7.0 (abort with ^G)
(app_name@127.0.0.1)1>
Is there way to start the node, maybe as a daemon on the dyno(s)?
Note I've tried to use start instead of console, but that did not yield any success.
So after much tinkering, trial and error, figured out what was wrong. Heroku does not like the interactive shell to be there - hence the crash on starting the Erlang app through console fails.
I've adjusted my Procfile, to the following:
# Procfile
web: erl -pa $PWD/ebin $PWD/deps/*/ebin -noshell -boot start_sasl -s reloader -s app_name -config ./rel/app_name/releases/1/sys
Which boots up the application app_name, using the the release's sys.config configuration file. What was crucial here, is to have the -noshell option in the command, that allows heroku to run the process as they expect it.